Apparatus for wrapping products with film

ABSTRACT

A wrapping apparatus for wrapping groups of products with a film includes conveyor elements for supporting and moving groups of products, a feeding unit for dispensing film portions of defined length through a transverse opening of the conveyor elements, a wrapping unit including a plurality of crossbars supported by respective rods and arranged for picking the film portions and wrapping the film portions around the groups of products and a hub arrangement, rotatable about a rotation axis and slidably supporting the rods to be mobile linearly and transversely to the rotation axis and rotatably about the rotation axis, the crossbars being moved along a wrapping trajectory, and a guiding assembly engaged by the rods and/or the crossbars for guiding the crossbars along the wrapping trajectory changing a distance of the crossbars from the rotation axis during a rotation of the respective rods.

The invention relates to apparatus for wrapping products with a plastic film and in particular relates to a wrapping apparatus that is associable with a heat-shrinkable plastic film packaging machine, in particular a bundling machine.

The known bundling machines allow wrapping groups of products of various shapes and dimensions, such as bottles, cans, jars, boxes, etc. with a film or pellicle made of heat-shrinkable plastic material, i.e. a material that is suitable to shrink or contract with heat, so as to wrap, compact and block each other the products.

The known bundling machines include a transporting system that moves the products to be packaged through a series of operating stations.

Downstream of a composing station, in which the products are divided and separated into groups of desired composition (for example in two or more side by side rows, each row including two or more products), a wrapping station is provided in which the groups of products are successively and individually wrapped with a portion of plastic film having a suitable length for forming respective bundles or packages. In a following heating station (shrinking tunnel or oven), the film portion wrapped around the products shrinks due to the heat so as to tightly wrap the products and carry out the final bundle or package.

The wrapping station includes a film feeding unit, which picks the film from a reel and cuts a film portion of suitable length, and a wrapping unit that picks and folds around the group of products said film portion that is obtained and dispensed by the feeding unit.

The feeding unit is positioned under a conveying or supporting plane of the bundling machine, on which the products are moved along an advancing direction. Through a first opening or slot of the conveyor plane, which is transverse to the advancing direction, the film portion is dispensed by the feeding unit so as to intercept the moving products. More precisely, a first front flap of the film portion is inserted under the group of moving products, which drag the film along the advancing direction.

The wrapping unit is provided with a plurality of wrapping transverse bars or crossbars, which are mobile longitudinally along a closed loop trajectory around the group of products, so as to pick, support and guide the film portion above and around the group of products. More precisely, once the group of products pass beyond the first transverse opening, a crossbar comes out from the conveyor plane through said first transverse opening so as to intercept and lift a rear flap of the film portion and fold the latter above the products, by moving along a first part of the closed loop trajectory. A second transverse opening, which is positioned downstream of the first transverse opening, allows the crossbar to entry under the conveyor plane and to insert the second rear flap of the film portion under the group of products, overlapping said second rear flap on the first front flap. The two overlapped flaps of film are blocked by the weight of products. Under the conveyor plane, inside the machine, the crossbar completes its closed loop trajectory by covering the second part thereof. Thus, the film that is unwound along the same longitudinal advancing direction wraps the products.

At the end of the wrapping, a bundle or package is obtained that leaves the group of products sideways open.

Different solutions are known for moving the crossbars for wrapping the film along the closed loop trajectory.

A first solution includes two driving chains, which are arranged parallel and opposite at both sides of the conveyor plane and provided with links to which the crossbars are fixed, suitably spaced. The motion trajectory of the crossbars coincides with the path of the chains.

In a second solution, the crossbar is cantilevered fixed to the end of an arm or rod, which is mounted on a hub around an axis that is horizontal and transverse to the conveyor plane so as to rotate on a substantially vertical plane. The motion trajectory of the crossbar that is fixed to the rotatable rod is circular or elliptical.

Generally, in the known wrapping units, the rod supports at the opposite ends two respective crossbars, whose distance is consequently fixed and equal to the length of the rod itself and to the distance between the two transverse openings of the conveyor plane. In some particular applications, one of the two crossbars can be dismounted.

A second rod, that is opposite to the first rod and parallel thereto, can be provided so as to support at both ends the crossbars and provide with greater stiffness and resistance the moving mechanism however without modifying the kinematics thereof.

In the bundling machines it is know the requirement of packaging products having different dimensions and sizes, for example bottles or cans or tins.

Products of different heights require modifying the position and/or the trajectory of the crossbars, in particular changing the distance thereof from the conveyor plane in order to correctly applying and folding the film.

Furthermore, in order to increase the production speed of the bundling machine in the case of small dimension products, it is necessary to modify also the packaging pitch, i.e. the distance between two successive groups of products and consequently between two successive crossbars.

In the wrapping units provided with chains for moving the crossbars it is possible to vary the height of the latter ones from the conveyor plane during the film wrapping (according to the height of product) and/or vary the pitch between the crossbars (according to the dimensions), by modifying the number of crossbars that are mounted along the path of the chain.

These wrapping units are therefore configurable according to the product or bundle size, but prevent the bundling machine to operate at high speeds, mostly because of the vibrations due to the mechanisms and to the operation of the chains moving the crossbars. For manufacturing high-speed machines, solutions are used in which the chains slides inside shaped channels, in these cases, however, being not possible to vary simply and quickly the trajectory of crossbars.

The wrapping units provided with rotating rods for supporting the crossbars have a simpler and cheaper construction and provide a greater precision of motion, but they do not allow modifying the angular distance between the crossbars (since only a configuration with two crossbars at 180° or with single crossbar is possible) and therefore to modify the pitch or distance between two groups of successive products.

There are wrapping units in which the rotating rod and the crossbars are connected and moved by motion adjusting means in such a way that the crossbars can move according to trajectories that are not circular, but arched and adjustable depending on the product size. More precisely, the crossbars are moved along an arched path with a distance from the conveyor plane that is variable and selectable. An apparatus of this type is disclosed in EP 1256519 of the same applicant.

However, these wrapping units with rotating rods for supporting the crossbars are complex and require, under the conveyor plane, sufficient room for rotating rod and crossbars in all the possible configurations. Furthermore, said wrapping units do not allow to modify the number of crossbars and the related angular distance in order to vary the pitch or distance between the products to be packaged.

An object of the invention is to improve the known wrapping units or apparatuses that are associable to packaging machines, in particular bundling machines, for wrapping a film made of heat-shrinkable plastic around groups of products to be packaged.

Another object is to carry out a versatile and flexible wrapping apparatus that allows to fold and wrap in a precise and efficient manner the film around products having different size and dimensions and/or to vary quickly and easily the packaging pitch, i.e. the distance between the products to be packaged, in particular for optimizing a production speed of the packaging machine.

A further object is to provide a wrapping apparatus having a structure that is simple, compact, with particularly small overall dimensions and at the same time having a precise and reliable operation.

Such objects and others are achieved by a wrapping apparatus according to one or more of the below disclosed claims.

The wrapping apparatus of the invention is associable with a packaging machine, in particular with a bundling machine, for wrapping a group of products with a film made of plastic material and includes conveyor elements for supporting and moving the products along a longitudinal advancing direction and forming a supporting plane for the products, a feeding unit of film that is arranged under the supporting plane for dispensing a film portion of defined length through a transverse opening of the conveyor elements so as to engage said products, and a wrapping unit for picking the film portion coming out from the transverse opening and wrapping the products with said film portion.

The wrapping unit includes a plurality of crossbars that are supported by respective rods and suitable to pick, support and guide respective film portions around the groups of products. The crossbars are transverse, in particular orthogonal, to the advancing direction and parallel to the supporting plane.

The wrapping unit also includes a hub arrangement that is rotatable around the rotation axis and slidably supports the rods so that the latter ones are mobile linearly and transversely to the rotation axis and rotatably about said rotation axis, the crossbars being so mobile along a closed loop wrapping trajectory. More precisely, the rods are coupleable in a removable manner to the hub arrangement so as to allow changing the number of said rods and of the respective crossbars and an angular distance between the rods around the rotation axis according to the dimensions of the groups of products and/or a pitch between the successive groups of products on the supporting plane.

The wrapping apparatus also includes guiding assembly engaged by the rods and/or the crossbars for guiding the latter ones along the wrapping trajectory by changing a distance of the crossbars from the rotation axis during a rotation of the respective rods.

Therefore, the wrapping trajectory of the crossbar is not a circular trajectory, but an arched and shaped trajectory that is defined by the guiding assembly, which can be easily replaced. More precisely, the guiding assembly is interchangeable, easily replaceable so as to change or modify the wrapping trajectory, in particular to change a first operating stretch of said trajectory that extends above the supporting plane. In this manner, it is possible to change displacement and position of the crossbar with respect to the supporting plane according to dimensions, or size, of the products to be packaged.

Products of great height, for example bottles for beverages, with respect to products of shorter height, such as cans or jars, require a film portion of bigger length, and consequently a first operating stretch of the wrapping trajectory of larger extension for wrapping, and a bigger distance of the crossbar from the supporting plane in said first operating stretch.

The operation of size change, i.e. the replacement of guiding assembly, is easy and simple and requires minimum downtime for the packaging machine.

It is also possible, by suitably choosing the guiding assembly, to create the wrapping trajectories that are most effective and appropriate for the products to be packaged according not only to dimensions and size, but also to the pitch between two successive groups of products.

The pitch of the products in the wrapping machine can be changed since the wrapping apparatus of the invention allows changing quickly and simply also the pitch, i.e. the angular distance, between two successive crossbars. In fact, the number of crossbars, i.e. the number of rods fixed to the hub arrangement, can be easily changed. More precisely, the supporting arms of the hub arrangement, which slidably support the rods, can be quickly mounted or dismounted to be angularly repositioned, in a smaller or larger number, so as to allow fixing a different number of rods and related crossbars.

Alternatively, the hub arrangement may include central bodies that are easily and quickly mountable and dismountable and interchangeable with a plurality of central bodies having a different number of supporting arms, so as to change the number of crossbars.

Therefore, by changing the number of crossbars and the related angular distance it is possible to change the pitch between the successive groups of products and thus increase or decrease the speed of the packaging machine according to the size of products.

Thanks to the wrapping apparatus of the invention, the packaging machine, which includes said apparatus, is suitable to package a wide range of products of different dimensions and s while optimizing the production speed or rate. More precisely, with small size product it is possible to reduce the pitch between the groups of products and increase the machine speed (up to values that are not suitable for large size products) so as to increase the productivity.

It should be noted that the wrapping apparatus of the invention has a simple and compact structure and further allows reducing and limiting the overall dimensions of the wrapping apparatus under the supporting plane, inside the packaging machine. This is made possible because the crossbars move separately and not in couple, since each crossbar is fixed to a respective rod, or a couple of opposite rods, and a second return stretch of the wrapping trajectory can be designed so as to be compact. On the contrary, in the known wrapping apparatuses, each rod supports at the opposite ends two separate crossbars and the trajectory of the crossbar under the supporting plane (second return stretch) is a consequence of the trajectory of the crossbar that moves above the supporting plane (first operating stretch) and that is imposed by the characteristics of the group of products to be wrapped. More precisely, in the wrapping apparatus of the invention, thanks to the rods that are slidably connected to the hub arrangement and thus during the rotation are mobile linearly and transversely, in particular orthogonally, to the rotation axis, the second return stretch of the wrapping trajectory can have a limited extension. In particular, the second return stretch can extend to a limited extent under the supporting plane since the rods are linearly displaced inwards along the respective supporting arms, towards the rotation axis. The overall dimensions of guiding assembly and rods under the supporting plane is therefore substantially defined by the length of the supporting arms of the hub arrangement, such length being much shorter than the summed length of supporting arms and rods in the maximum extension position in the first operating stretch of the wrapping trajectory.

The invention will be better understood and implemented with reference to the attached drawings, which illustrate an exemplifying and non-limiting embodiment, wherein:

FIG. 1 is a schematic perspective view of the wrapping apparatus of the invention installable on a packaging machine;

FIG. 2 is a side view of the apparatus of FIG. 1;

FIG. 3 is a section view along the line of FIG. 2;

FIG. 4 is a schematic section view of the apparatus of FIG. 1 associated to a group of products to be wrapped and in an operating step;

FIG. 5 is a perspective view of the wrapping apparatus of FIG. 1;

FIG. 6 is a schematic section view of a different configuration of the apparatus of FIG. 5 that is associated to a group of products to be wrapped and in an operating step.

With reference to FIGS. 1 to 6, the wrapping apparatus 1 of the invention is shown that is associated with a packaging machine 100, in particular a bundling machine, for wrapping with a film 50 made of plastic material, in particular of heat-shrinkable type, groups 61 of products 60 so as to form respective bundles or packages of products. More precisely, the wrapping apparatus 1 can be used and installed in a wrapping station of the packaging machine 100, interposed between a composing or forming station of groups of products to be wrapped, in which the products are divided and separated so as to form groups of desired composition, and a successive heating station, in which the film wrapped around each group of products 60 contracts and shrinks because of the heat so as to tightly wrap the products and carry out the bundle.

The composing station and the heating station are of known type and not illustrated in the figures.

The wrapping apparatus 1 includes conveyor elements 21, 22, 23 for supporting and moving groups 61 of products 60 along an advancing direction A, longitudinal and substantially horizontal, a feeding unit 2 of film 50 for dispensing film portions 51 of defined length, and a wrapping unit 3 suitable to pick the film portions 51 and wrap with the latter ones the groups 61 of products 60.

With reference to the embodiment shown in the figures, the conveyor elements include three distinct conveyors or transporting belts that are arranged aligned and in succession along the advancing direction A.

A first conveyor 21 receives the group 61 of products 60 from the upstream forming station and transfers said group 61 of products 60 to a successive second conveyor 22 that moves the products 60, while the latter ones are wrapped by the film portion 51. A third conveyor 23 receives the group 61 of products 60 wrapped in the film 51 and moves said group 61 of products towards the successive heating station that is arranged downstream. The three conveyors 21, 22, 23 moving the products 60 along the advancing direction A at the same speed, have respective supporting surfaces that form a substantially horizontal supporting plane 20 for said products 60.

The feeding unit 2, of known type and not illustrated in detail in the figures, is positioned under the supporting plane 20 and includes means for unwinding the plastic film 50 from a reel and for cutting a portion 51 thereof having a suitable length and such as to allow wrapping the group 61 of products 60 properly and completely. The feeding unit 2 dispenses the cut film portion 51 through a transverse opening 24 of the conveyor elements 21, 22, 23 so as to catch and engage the products 60.

More precisely, the feeding unit 2 dispenses the film portion 51 so that a first front flap thereof is inserted under the products 60 moving on the conveyor elements 21, 22, 23. The transverse opening 24 is a slot or slit that is transverse, in particular orthogonal, to the advancing direction A, and separates the first conveyor 21 from the second conveyor 22. A further transverse opening 25 is provided for separating the second conveyor 22 from the third conveyor 23. The further transverse opening 25 is a respective slot or slit that is transverse, in particular orthogonal, to the advancing direction A.

The wrapping unit 3 includes a plurality of transverse bars or crossbars 4, which are arranged transversely, in particular orthogonally, to the advancing direction A for picking, supporting and guiding respective film portions 51 around the groups 61 of products 100. Each crossbar 4 is connected to an end portion 15 of a respective rod 5 that is mounted rotatable around a rotation axis X, which is substantially horizontal and transverse, in particular orthogonal, to the advancing direction A. In such manner, the rods 5 rotate on an almost vertical plane and the respective crossbars 4 are fixed to the rods 5 so as to be parallel to the rotation axis X and parallel to the supporting plane 20.

In the embodiment shown in the figures, the wrapping unit 3 includes three crossbars 4 that are angularly spaced around the axis X, in particular by 120°, and connected to respective couple of rods 5. More precisely, each crossbar 4 is supported and fixed at its opposite ends to two respective rods 5, which are both rotatable around the axis X and arranged parallel and mutually facing at the two opposite sides of conveyor elements, in particular of the second conveyor 22. The rods 4 of each side of the conveyor elements 21, 22, 23 are angularly spaced each other by 120° around the axis X.

Alternatively, the crossbars 4 can be cantilevered fixed to only one respective rod 5, the rods 5 being in this case provided at only one side of the conveyor elements 21, 22, 23.

During the rotation of rods 5 around the rotation axis X, the crossbars 4 are thus moved along a defined closed loop wrapping trajectory T, around the group of products 60 moving on the second conveyor 22 along the advancing direction A and through the transverse openings 24, 25 of the supporting plane 20, as better explained in the description below.

The wrapping trajectory T of the crossbars 4 includes a first operating stretch T1 extending above the supporting plane 20 and the products 60 and a second return stretch T2 extending below the supporting plane 20.

The wrapping unit 3 also includes a hub arrangement 8, rotatable around the rotation axis X and slidably supporting the rods 5 so that the latter ones are mobile linearly and transversely to the rotation axis X, in particular orthogonally to the latter, and rotatably about the rotation axis X.

The apparatus includes a guiding assembly 6, 7 that is engaged by the rods 5 and/or by the crossbars 4 for guiding the latter ones along the wrapping trajectory T, changing a distance of the crossbars 4 from the rotation axis X during a rotation of rods 5, i.e. during the movement of crossbars 4 along the wrapping trajectory T.

The rods 5 are coupleable in a removable manner to the hub arrangement 8 so as to change the number of rods 5 and of respective crossbars 4 and an angular distance between the rods 5 around the rotation axis X according to the dimensions of the groups 61 of products 60 and/or a pitch or distance p between two successive groups 60 of products 61 on the supporting plane 20, as better explained in the description below.

More precisely, each crossbar 4 is fixed to the end portion 15 of the respective rod 5 that is removably connected to the hub arrangement 8 by means of a respective supporting arm 28 suitable to slidably support said rod 5 transversely, in particular orthogonally, to the rotation axis X.

The hub arrangement 8 includes at least a central body 27 that is rotatably connected to a frame 10 of the wrapping unit 3, so as to rotate about the rotation axis X driven by actuating means 35, including for example an electric rotary motor. In the embodiment shown in the figures, the hub arrangement 8 includes two central bodies 27 that are rotatably connected to the frame 10 at the opposite sides of conveyor elements 21, 22, 23 and are both driven by actuating means 35.

Each central body 27 includes a fastening assembly 26 for removably fastening a desired number of supporting arms 28. Each supporting arm 28 is arranged for slidably supporting a respective rod 5 that is linearly mobile along an adjusting direction, which is almost orthogonal to the rotation axis X. In particular, the supporting arms 28 are tangentially fastened to the central body 27. Alternatively, the supporting arms 28 can be radially fastened to the central body 27.

In the illustrated embodiment, the supporting arms 28 are provided with respective carriages 29, for example provided with sliding rollers or spheres, which slidably engage and support the corresponding rods 5, formed by suitable shaped rails. The linear coupling between the carriages 29 and the shaped rails of rods 5 guarantees the linear sliding of the latter ones along the adjusting direction and parallel to the supporting arm 28.

The supporting arms 28 can be easily dismounted from the fastening assembly 26 of the central body 27 that includes fastening elements such as holes for screws, plugs and similar elements, so as to be angularly positioned in a smaller or larger number and enable to fix a different number of rods 5 and related crossbars 4. More precisely, the fastening assembly includes a plurality of fastening elements 26 that are mutually angularly spaced around the rotation axis X, a supporting arm 28 being reversibly fastenable to a respective fastening element 26.

As shown in FIG. 4, each fastening element 26 includes, for example, a group of fastening holes for screws, plugs and similar elements that are carried out on a wall of the central body 27, said groups of fastening holes enabling to fasten to each central body 27 of the hub arrangement 8 three supporting arms 28 that are regularly angularly spaced from each other, in particular by 120° or, as shown in FIG. 6, two supporting arms 28, regularly angularly spaced from each other, in particular by 180°.

The number and the angular distribution of the groups of fastening holes 26 on the central bodies 27 can however be such as to allow fastening a larger number of supporting arms 28, i.e. of crossbars 4, for example four or five.

The number of crossbars 4 can be chosen, in fact, according to the pitch p and the size of the groups 61 of products 60 to be packaged, for example can be increased for reducing the pitch p between two successive groups of products 60 so as to increase speed and productivity of the packaging machine 100.

In a variant of the wrapping apparatus that is not illustrated in the figures, the hub arrangement 8 includes at least a central body 27, more precisely two central bodies 27 that are arranged on opposite sides of conveyor elements 21, 22, 23, each central body 27 being provided with a set number of supporting arms 28 for respective rods 5 and crossbars 4 and in this case fixed in a removable and reversible manner to the frame 10 and interchangeable with further central bodies 27 having different number of supporting arms 28. In this case, the supporting arms 28 are fixed to, or carried out as a single body with, the central body 27. The central body 27 can be disengaged, for example, along the rotation axis X.

The guiding assembly includes at least a guiding element 6 arranged on the side of the conveyor elements 21, 22, 23 and provided with an annular seat 11, which extends along the wrapping trajectory T and is suitable to slidably receive a coupling element 14 that is fixed to each crossbar 4 or related rod 5. More precisely and in the illustrated embodiment, the end 15 of each rod 5 includes a shaped portion, for example a lever shaped portion, to which the respective crossbar 4 and the respective coupling element 14 are fixed. Alternatively, the coupling element 14 can be directly associated to the crossbar 4, fixed at one end thereof.

In the illustrated embodiment, the guiding assembly includes two guiding elements 6, 7 that are arranged facing, and fixed to the frame 10 at opposite sides of the conveyor elements 21, 22, 23. In particular, the guiding assembly includes, in addition to the guiding element 6, a further guiding element 7 provided with a further seat 12, which is substantially specular to the seat 11 and arranged for slidably receiving the corresponding coupling elements 14 of rods 5.

The two guiding elements 6, 7 support and guide the opposite ends of crossbars 4 and, more precisely, the ends 15 of the couple of rods 5 of each crossbar 4.

Each guiding element 6, 7 includes, for example, a respective curvilinear shaped element, which forms a closed and shaped loop and is provided with an annular groove 11, 12 forming the seat suitable to receive the coupling elements 14 of the end portions 15 of rods 5, said coupling elements 14 including, for example, respective rolls or wheels idly mounted on the end portions 15.

Each guiding element 6, 7 is essentially a positive cam, or channel cam, that is provided with a respective groove or seat 11, 12 (channel) which the rolls 14 of the rods 5 engage. In this manner, during the rotation around the rotation axis X, each rod 5, which is engaged with the end portion 15 by the respective roller 14 to the seat 11, 12 of the guiding elements 6, 7, slides linearly and orthogonally to the rotation axis X, allowing the crossbar 4 moving along the wrapping trajectory T coinciding with the path or track of the seat 11, 12.

Each guiding element 6, 7 includes a first upper portion 16, 17, suitable to support and guide the crossbars 4 along the first operating stretch T1 of the wrapping trajectory T, and a second lower portion 18, 19, suitable to support and guide the crossbars 4 along the second return portion T2 of the wrapping trajectory T.

The first upper portion 16, 17 is removably connected to the second lower portion 18, 19 for forming the respective guiding element 6, 7 and is interchangeable with one of a plurality of first upper portions having different respective annular seats 11, 12 so as to change or modify the first operating stretch Ti of the wrapping trajectory T and then a position of the crossbar 4 with respect to the supporting plane 20, in particular according to a dimension or size of the products 60 to be packaged.

Also the second lower portion 18, 19 can be dismounted from the wrapping unit in order to modify the second return stretch T2 of the wrapping trajectory T.

In a version of the apparatus 1 not shown in the figures, the first upper portion 16, 17 and the second lower portion 18, 19 are fixed so as to carry out a single body. In this case, the whole guiding element 6, 7 is fixed in a removable manner to the frame 10 of the wrapping unit 3 and is interchangeable with one of a plurality of guiding elements provided with respective different seats 11, 12 for changing and modifying the wrapping trajectory T.

FIG. 6 illustrates a different configuration of the wrapping apparatus 1 of the invention in which the wrapping unit 3 includes two crossbars 4 that are supported by two respective couple of rods 5, angularly spaced by 180°. In this variant, two respective supporting arms 28 are fastened to the fastening assembly 26 of the two central bodies 27 of the hub arrangement 8, and are tangentially fixed and angularly spaced by 180°. The two crossbars 4 are supported and guided at the respective ends by the two guiding elements 6, 7. More precisely, the rolls 14 of the end portions 15 of rods 5 slide inside the seats 11, 12 of the guiding elements 6, 7 causing the rods sliding on the supporting arms 28 during the rotation around the axis X.

The different number of crossbars 4 and the related angular distance (180° allows increasing the pitch p between two successive groups 61 of products 60, for example because the latter ones have larger dimensions. With respect to the configuration with close pitches that is illustrated in FIG. 4, the speed of the machine can be reduced in order to not destabilize the products 60 when moving.

The number of the crossbars 4 can be increased, according to pitch and size of the groups of products to be packaged for allowing reducing, in this case, the pitch between two successive groups of products 60 and increasing speed and productivity of the packaging machine 100.

The operation of the wrapping apparatus 1 of the invention mounted on a packaging machine 100, in particular in a wrapping station thereof, includes moving the groups 61 of products 60 coming from the forming station along the first conveyor 21 towards the second conveyor 22, on the supporting plane 20. At the transverse opening 24, which is interposed between the first conveyor 21 and second conveyor 22, a front or forward portion of the group of products catches a portion 51 of the film 50 of suitable length that is dispensed by the feeding unit 2. More precisely, a first front flap of the film portion 51 is inserted under the moving group 61 of products 60 and dragged along the advancing direction A.

Once the group of products is transferred onto the second conveyor 22, a crossbar 4 supported by a respective couple of rods 5 comes out from the supporting plane 20 through the transverse opening 24 so as to intercept and lift a second rear flap of the film portion 51 and fold the latter above, and longitudinally around, the group 61 of products 60, moving along the first operating stretch T1 of the closed loop wrapping trajectory T.

More precisely, the crossbar 4 is supported at the opposite ends and moved along the wrapping trajectory T by a respective couple of rods 5, which are rotatable around the rotation axis X and linearly slidable orthogonally thereto. More precisely, the linear movement of rods 5 during the rotation is carried out by the coupling elements 14 slidably coupling with the seats 11, 12 of guiding elements 6, 7. Basically, the guiding elements 6, 7 are two positive cams provided with respective grooves or seats 11, 12 in which said coupling elements 14 are engaged.

Continuing the movement along the wrapping trajectory T, the crossbar 4 returns under the moving plane 20 through the further transverse opening 25 so as to insert the second rear flap of the film portion 51 under the group of products 60, overlapping the aforesaid second rear flap to the first front flap. The two overlapped flaps of the film portion 51 are blocked by the weight of the products.

Under the supporting plane 20, inside the packaging machine 100, the crossbar 4 completes the wrapping trajectory T by covering the second return stretch T2.

It should be noted that the wrapping trajectory T of the crossbar 4 is not a circular trajectory, but a shaped trajectory that is defined by the guiding assembly 6, 7 that can be easily replaced. More precisely, the upper portions 16, 17 of the guiding elements 6, 7, which guide the rods 5 and then the crossbars 4 along the first operating stretch T1, are interchangeable, easily replaceable with first upper portions 16, 17 having different seats 11, 12 so as to change or modify such first operating stretch T1. In this manner, it is possible to change the displacement and the position of crossbar 4 with respect to the supporting plane 20 according to dimensions, or size, of the products 60 to be packaged.

Products of great height, for example bottles for beverages, with respect to products of shorter height, such as cans or jars, require a film portion 51 of bigger length and consequently a first operating stretch T1 of larger extension for wrapping, and a bigger distance of the crossbar 4 from the supporting plane 20 in said first stretch T1.

The operation of size change, i.e. the replacement of first upper portions 16, 17 (or alternatively of the complete guiding elements 6, 7), is easy and simple and requires minimum downtime for the packaging machine 100.

By suitably choosing the path of the seats 11, 12 of guiding elements 6, 7, it is also possible to obtain the wrapping trajectories T that are more effective and appropriate for the products to be packaged according not only to dimensions and size, but also to the pitch p between two successive groups 61 of products 60.

In fact, it is possible to change the pitch of the groups 61 of products 60 in the wrapping machine 100 since the wrapping apparatus 1 of the invention allows modifying in a fast and simple manner the number of crossbars 4, i.e. of rods 5 fixed to the hub arrangement 8. More precisely, the supporting arms 28, thanks to the fastening assembly 26, can be quickly and easily mounted on, or dismounted from, the central bodies 27 of the hub arrangement 8 so as to be angularly repositioned, in a smaller or larger number, and to enable to fix a different number of rods 5 and related crossbars 4.

Therefore, by changing the number of crossbars 4 and the related angular distance it is possible to change the pitch p between two successive groups 61 of products 60 and then to increase or decrease the speed of the packaging machine 100 according to the product size.

Thanks to the wrapping apparatus 1 of the invention the packaging machine 100 can package a wide range of products 60 and groups 61 of products 60 having different dimensions and sizes, while optimizing the production speed or rate. More precisely, with small size products it is possible to reduce the pitch p between the groups of products and increase the machine speed (up to values that are not suitable for large size products) so as to increase the productivity.

Finally, it should be noted that the wrapping apparatus 1 of the invention has a simple and compact structure and further allows reducing and limiting the overall dimensions of the wrapping unit 3 under the supporting plane 20, inside the packaging machine 100.

Thanks to the rods 5, which are slidably connected to the hub arrangement 8 and then linearly mobile during the rotation around the rotation axis X transversely, in particular orthogonally, to the latter, the second return stretch T2 of the wrapping trajectory T can have a limited extension. More precisely, such second return stretch T2 extends to a limited extent under the supporting plane 20, since the rods 5 are linearly moved along the respective supporting arms 28 inwardly toward the rotation axis X, so that the end portions 15 are adjacent to the carriages 29. The overall dimensions of the guiding assembly 6,7 and rods 5 under the supporting plane 20 is therefore substantially defined by the length of the supporting arms 28, which is much shorter than the summed length of the supporting arms 18 and rods 5 in the position of maximum extension in the first operating stretch T1. 

1-14. (canceled)
 15. A wrapping apparatus associable with a packaging machine for wrapping with a film made of plastic material groups of products, including: conveyor elements for supporting and moving said groups of products along a longitudinal advancing direction and forming a supporting plane of said products; a film feeding unit positioned under said supporting plane for dispensing film portions of defined length through a transverse opening of said conveyor elements so as to engage said groups of products; a wrapping unit that includes a plurality of crossbars, each of which supported by at least a respective rod, wherein said crossbars are arranged for picking said film portions that come out from said transverse opening and wrapping said film portions around said groups of products, an hub arrangement that is rotatable about a rotation axis and slidably supports said rods of said crossbars so that said rods are mobile linearly and transversally to said rotation axis and rotatably about said rotation axis and said crossbars are consequently moved along a defined closed loop wrapping trajectory; and a guiding assembly engaged by said rods and/or by said crossbars for guiding the latter ones along said wrapping trajectory changing a distance of said crossbars from said rotation axis during a rotation of said respective rods; wherein said apparatus can be coupled in a removable manner to said hub arrangement so as to change a number of said rods and of said respective crossbars and an angular distance between said rods around said rotation axis according to dimensions of products and/or a pitch between successive groups of products on said supporting plane.
 16. The wrapping apparatus according to claim 15, wherein said crossbars are transverse to said advancing direction and parallel to said supporting plane.
 17. The wrapping apparatus according to claim 15, wherein each crossbar is fixed to an end portion of a respective rod that is removably connected to said hub arrangement by means of a respective supporting arm that is suitable to slidably support said rod transversely to said rotation axis.
 18. The wrapping apparatus according to claim 17, wherein the hub arrangement includes a central body that is rotatably connected to a frame of said wrapping unit about said rotation axis and includes a fastening assembly for removably fastening a desired number of supporting arms for respective rods.
 19. The wrapping apparatus according to claim 17, wherein said hub arrangement includes at least a central body that is rotatably connected to a frame of said wrapping unit about said rotation axis and is provided with a definite number of supporting arms for respective rods, and said central body is removably fixed to said frame and interchangeable with one of a plurality of central bodies which have a different number of supporting arms.
 20. The wrapping apparatus according to claim 15, wherein each crossbar is fixed to end portions of a respective couple of rods that are removably connected to said hub arrangement through respective supporting arms at opposite sides of said conveyor elements.
 21. The wrapping apparatus according to claim 20, wherein said hub arrangement includes two central bodies rotatably connected to a frame about said rotation axis at opposite sides of said conveyor elements, wherein each central body includes a fastening assembly for reversibly fastening a desired number of supporting arms and rods or wherein each central body is removably fastened to said frame and is interchangeable with one of a plurality of central bodies which have a different number of supporting arms.
 22. The wrapping apparatus according to claim 18, wherein said fastening assembly includes a plurality of fastening elements, which are mutually angularly spaced around said rotation axis, and a supporting arm is reversibly fixed to the respective fastening element.
 23. The wrapping apparatus according to claim 21, wherein said fastening assembly includes a plurality of fastening elements, which are mutually angularly spaced around said rotation axis, and a supporting arm is reversibly fixed to the respective fastening element.
 24. The wrapping apparatus according to claim 15, wherein said guiding assembly includes a guiding element that is arranged on a side of said conveyor elements and provided with a seat that extends along said wrapping trajectory and is arranged to slidably receive a coupling element of said rod and/or of said crossbar.
 25. The wrapping apparatus according to claim 15, wherein said guiding assembly includes a couple of guiding elements arranged on opposite sides of said conveyor elements and provided with respective seats that extends along said wrapping trajectory and is arranged for slidably receiving a coupling elements of said rod and/or of said crossbar.
 26. The wrapping apparatus according to claim 24, wherein said guiding element includes a first upper portion suitable for supporting and guiding said crossbar along a first operating stretch of said wrapping trajectory that extends above said supporting plane, and a second lower portion for supporting and guiding said crossbar along a second return stretch of said wrapping trajectory that extends under said supporting plane.
 27. The wrapping apparatus according to claim 24, wherein said guiding element is removably fixed to a frame of said wrapping unit and is interchangeable with one of a plurality of guiding elements provided with respective seats in order to modify said wrapping trajectory.
 28. The wrapping apparatus according to claim 27, wherein said first upper portion of said guiding element is removably connected to said second lower portion and interchangeable with one of a plurality of first upper portions in order to modify said first stretch of said wrapping trajectory.
 29. Bundling packaging machine for wrapping a plurality of products with a film made of plastic material, that includes a wrapping apparatus according to claim
 15. 